Flying in Close Formation

The TanDEM-X operational scenario requires the coordinated operation of two satellites flying in close formation. Super resolution require selectable along-track baselines in the range from hundred meters up to several kilometers. Interferometric data acquisition can be achieved with the TanDEM-X satellite formation. This formation combines an out-of-plane ( horizontal ) orbital displacement by different ascending nodes with a radial ( vertical ) separation by different eccentricity vectors resulting in a helix like relative movement of the satellites along the orbit.

Interferometric SAR Observational Modes

Interferometric data acquisition with the TanDEM-X satellite formation can be achieved in three operational modes: Pursuit monostatic mode, bistatic mode and alternating bistatic mode. (a) Pursuit monostatic mode: Both SAR are operated independently for synchronization needs, SAR instruments look acquire data from the same swath with a short time difference of a few seconds corresponding to an along-track distance of 30-50 km,the temporal decorrelation is small for most terrain types with the exception of ocean surfaces and vegetation in the case of moderate to high wind speeds. (b) Bistatic mode: Where the SAR instruments of both spacecraft look into a common footprint thus providing different views of the observed target area.This enables the acquisition of highly accurate single-pass cross-track and/or along-track interferograms without the inherent accuracy limitations imposed by repeat-pass interferometry due to temporal decorrelation and atmospheric disturbances. (C) Alternating bistatic mode: It is similar to bistatic mode, but the transmitter is switched from pulse to pulse between the two satellites.It can be used for phase synchronization, system calibration, and to acquire interferograms with two different phase to height sensitivities; the simultaneously acquired monostatic interferogram has a higher susceptibility to ambiguities especially at high incident angles.


  • Repeat cycle
    11 days

  • Center frequency
    9.65 GHz / X band

  • Wavelength
    3.1 cm

  • Look direction
    L & R

  • Incidence angle
    20 to 60°

  • Imaging mode
    7 types

  • Resolution
    0.25 to 40 m

  • Polarization
    Single / Dual

Imaging Modes

The standard TerraSAR-X operational mode is the single receive antenna mode from which the following imaging modes can be retrieved: SpotLight, StripMap, and ScanSAR. The single receive antenna mode uses a chirp bandwidth of up to 300 MHz.

Imaging Modes

Beam Mode Polarization Resolution ( m ) Scene
Size ( km )
Full Performance
Range ( ° )
Slant Range Azimuth
Staring SpotLight HH or VV 0.25 0.25 4 X 3.7 20 to 60
HH / VV 0.25 0.25
High Resolution
Spotlight 300 MHz
HH or VV 0.6 1.1 5 X 7 - 10 20 to 55
High Resolution Spotlight HH or VV 1.2 1.1 5 X 10
HH/ VV 1.2 2.2
SpotLight HH or VV 1.2 1.7 10 X 10
HH/VV 1.2 3.4
StripMap HH or VV 1.2 3.3 30X50 20 to 45
HH / VV or
HH / HV or
1.2 6.6 15X50
ScanSAR HH or VV N / A 18.5 100 X 150
Wide ScanSAR HH or VV 40 40 270 X 200

Programming Services

Programming Level Description
Standard Order confirmation up to 3 days before submission deadline
Fast Order confirmation sent between 3 and 1 day before submission deadline
Urgent Order confirmation sent less than 1 day before submission deadline
* Submission deadlines are 08:30 UTC and 21:30 UTC or as indicated in the financial quotation

Modification and Cancellation Policy

Modification and Cancellation Notice
Before 24 h prior to submission deadline
Within 24 h prior to submission deadline
* Modification and cancellation notice must be submitted in written format via e-mail or fax
** Submission deadlines are 08:30 UTC and 21:30 UTC

Processing Services

Processing Level Description
Regular: Science Orbit Within 7 day
Regular: Rapid Orbit Within 1 day
NRT: Predicted Orbit Under 7 hours
* From time of acquisition to data made available on a pick-up point

Unprecedented Resolution Up to 25 cm

The new TerraSAR-X Staring SpotLight mode ( High Resolution SpotLight ) takes SAR-based object detection and recognition for Image Intelligence ( IMINT ) and GEOINT applications to a new level. An unprecedented resolution of down to 0.25 metres and enhanced radiometric quality reveal the crucial details. High Resolution SpotLight mode is made for professionals who require highly detailed and reliable all-weather information for dependable decision making.